Electronic Structures and Optical Properties for Nano Particles: Experimental and Theoretical Calculations

Abstract

The use of copper nanoparticles (Cu NPs) and copper oxide nanoparticles (Cu2O NPs) has increased dramaticallyboth in the medical and industrial fields. In the present study, we have used various techniques like, dynamic light scattering(DLS) for particle size, zeta potential determination, X-ray diffraction (XRD), transmission electron microscope (TEM) andscanning electron microscope (SEM) for development and characterization of Cu and Cu2O NPs. We have also performed theab-initio calculations based on the density functional theory (DFT) where the theoretical results are in well accordance with theexperimental reports. The Hubbard correction is included over the generalized gradient approximation (GGA) for a betterdescription of Cu and Cu2O NPs. The plot of densities of states (DOS) and energy band structures of Cu and Cu2Onanocrystals predicts the metallic and semiconducting nature of Cu and Cu2O, respectively. The energy bands and DOS showsstrong hybridization of Cu-O and predicts the metallic nature of Cu and semiconducting nature of Cu2O. The optical absorptionresults show that both the Cu2O and Cu samples are absorbing strongly at the minimum energy. The band structure of Cu Nanocrystals reveals a metallic nature where the valence band crosses the Fermi energy level at W point. However, an indirectenergy band gap can be seen above the EF.